JPH0757742B2 - Method for producing ethercarboxylic acid from carbohydrate and its derivative - Google Patents

Abstract

Detergent compositions containing ether-carboxylic acids which are prepared by oxalkylating carbohydrates and derivatives thereof followed by oxidation, either by immediately ethoxylating the carbohydrates or the derivatives thereof in the customary manner or by first alkoxylating the carbohydrates or the derivatives thereof with a higher alkylene oxide and then ethoxylating the product, and oxidising the resulting aqueous solution without further treatment with oxygen as the oxidant in the presence of a catalyst comprising at least one platinum metal in a pH range in which the carbohydrates and the carboxylic acids derived therefrom are stable.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the ethoxylation of carbohydrates (Oxthylierung).
And a method for producing an ethercarboxylic acid by subsequent catalytic oxidation.

Due to the eutrophication effect of lakes and rivers (Gewssern),
The use of phosphates in detergents and cleaners (Reinigungsmittel) is legally restricted in some countries and partly even prohibited. Therefore, in the meantime, numerous substitutes for phosphates, especially sodium tripolyphosphate, have been developed and proposed as builders (Gerstsoff). However, the desired properties of sodium tripolyphosphate as a detergent application have hitherto not been completely achieved from a single substance. Rather, only a combination of builders can achieve the phosphate effect as a first approach. Only relatively few phosphate substitutes-or better said partial substitutes-can be sufficiently satisfied with regard to ecological properties. Even if eutrophication of lakes and rivers is not promoted, they must nonetheless be regarded as properties that, in part, should be considered dangerous to the environment, for example:
Has heavy metal remobilization or inadequate biodegradability from lake and river sediments; therefore, even if these substances are toxic for the time being, according to current knowledge levels. Even if they cannot be considered at all, their environmental relevance is not certain. Therefore, there is an ongoing search for detergent-effective builders that may be considered safe in terms of their ecological effects.

From JP-A-58-117284, coal can be produced by reacting polyhydric alcohols, which also include carbohydrates, into polyether compounds by reaction with alkylene oxides, and optionally subsequently converting the terminal hydroxyl groups to carboxyl groups, coal So-called viscosity reducing agents for sludges are known; however, more precise details regarding the synthesis of these products are not available.

The ethoxylation of carbohydrates has been known for a long time.
Thus, for example, W.Gerhardt, Jfprakt.Chem, fourth series, 29, 300 (1965) describes the ethoxylation of saccharose;. Sho 58-117284 discloses still further mentioned carbohydrates is doing. However, no economical process for the production of oxidized ethoxylates of carbohydrates and the use of such products as builders is heretofore known.

The object of the present invention was therefore to develop a biodegradable phosphate substitute and a production process which can be implemented economically and industrially.

Surprisingly, it now has a good lime binding capacity,
Biologically degradable phosphate substitutes ethoxylate carbohydrates, optionally under additional alkoxylation with higher alkylene oxides, and convert terminal primary hydroxyl groups to carboxyl groups by catalytic oxidation. It has been found that the benefits are obtained when changing.

The subject of the invention is therefore the direct ethoxylation of the carbohydrates or their derivatives in the usual way, or first of all the alkoxylation with higher alkylene oxides and then the ethoxylation and the further treatment of the resulting aqueous solution. Without oxidation, in the presence of a catalyst containing at least one platinum group metal with oxygen as oxidizing agent in the pH range where the carbohydrate and the carboxylic acid derived therefrom are stable, A process for producing ether carboxylic acids by the alkoxylation and subsequent oxidation of carbohydrates and their derivatives.

The ethercarboxylic acids prepared according to the process according to the invention are particularly suitable as builders in detergents and cleaners because of their surprisingly high lime-binding capacity.

As a starting material, practically all carbohydrates having at least one hydroxyl group which can be alkoxylated and one alcohol group which can be oxidized to a carboxyl group, eg glucose, galactose, maltose,
Lactose, fructose, β-cyclodextrin,
Sucrose is particularly suitable. Examples of the derivatives include α-methyl-D-glucoside, sorbitol, mannitol, 2-Desoxy-D-ribose and D-glucosamine.

Ethoxylation and alkoxylation are conventional methods,
That is, generally in an aqueous solution under the action of a basic catalyst
It is carried out at temperatures between 0 ° C., preferably in the pressure range from atmospheric pressure to 15 bar. The solution containing the compound having a terminal hydroxyethyl group is preferably diluted to a water content of 70 to 90% by weight and then subjected to catalytic oxidation to form an ethercarboxylic acid. Suitably at least 50% of the hydroxyl groups of carbohydrates and their derivatives, preferably at least
75%, and especially about 100%, should be alkoxylated.

Among the higher alkylene oxides, butylene oxide, styrene oxide and, above all, propylene oxide are of concern. They can be used, for example, in amounts of up to 3 mol, preferably at least 0.1 mol. Of course, some higher alkylene oxides are preferably selected to ensure biodegradability.

Ethylene oxide is preferably at least 1 mole,
For example, it is used in an amount of up to 10 moles, and preferably up to 5 moles. All molar designations then relate to the number of moles of hydroxyl groups contained in the carbohydrate or its derivatives. If these are first of all reacted with alkylene oxides other than ethylene oxide,
The total amount of alkylene oxide to be reacted, including ethylene oxide, is preferably 5 mol or less.

Suitable catalysts are those which contain platinum group metals, ie osmium, iridium, rhodium, ruthenium, palladium and / or platinum. Preference is given to a combination of palladium and platinum and especially a catalyst containing only platinum.
Preferably, the platinum group metal is supported on a support such as Al ₂ O ₃ or SiO ₂ , especially on activated carbon. The metal content of the catalyst is generally 1 to 15, preferably 5 to 10% by weight.
Is.

Occasionally, especially when poorly water-soluble carbohydrate derivatives are used as starting materials, solubilizers which are inert under the reaction conditions are preferably added to the amount of water and solubilizer of preferably 10-75. It may be suitable to add in a concentration of wt.%, In particular 30 to 50 wt.%. Solubilizers that are less volatile when oxygen is introduced through the aqueous solution and therefore sufficiently avoid the danger of explosion in the steam chamber are first of all suitable; After the agent is oxidized,
It is desirable to be able to separate easily, for example by distillation. Suitable solubilizers are, for example, glycol ethers without OH groups, for example those of the formula R ¹ O (CHRCH ₂ O) _n R ² where n is a number from 1 to 4 and R is H. Or CH ₃ and R
¹ and R ² independently of _one another mean C ₁ -C ₄ -alkyl. Particularly suitable are the dimethyl-, diethyl- and methyl-ethyl-ethers of the general formula above having a boiling point in the range of 100 to about 250 ° C., for example triethylene glycol dimethyl ether and preferably diethylene glycol dimethyl ether.

The preferred oxidant is pure oxygen. However, it is also possible to use a mixture of oxygen and a gas which is inert under the reaction conditions in question, for example a mixture of oxygen and an inert gas. Of course, the air itself is also suitable.

Generally, the oxidation is carried out at a total pressure of 0.5-100 bar. The reaction rate clearly increases with increasing oxygen partial pressure;
However, the advantage of higher reaction rates can be overcompensated for economic effectiveness by the higher instrument costs required when using higher pressures. A pressure range from atmospheric pressure to 10 bar (absolute) is preferred, the work being carried out particularly easily at atmospheric pressure.

Oxidation is generally 5 to 80 ° C, preferably 10 to 60 ° C, especially
It is carried out at a temperature of 20-40 ° C. Since the safety of many carbohydrates and the carboxylic acids derived from them is low in the acidic range, the oxidation is almost neutral to weakly alkaline medium.
That is, 5-9, preferably 6-8.5 and especially 7-8
It is preferred that it is carried out in the pH range of. Carboxylic acids generated during oxidation are, for example, by suitable buffer substances,
Alternatively or preferably, it is suitable to be trapped by the addition of an aqueous base, for example an alkali- or alkaline earth metal hydroxide-solution, where these are the pH of the reaction system.
It is preferred that the values are arranged such that they are in the range 6-9 during oxidation. Upon complete neutralization, the oxidation products are then present as salts.

The process according to the invention can be carried out in all equipment which is suitable for carrying out the reaction in the liquid phase with or without overpressure. Examples of this are the practice in stirred vessels with suspended catalyst or in bubble columns. However, the oxidation can also be carried out in a Rieselphasenreaktor in a solid bed with granular catalyst.

The required reaction time is preferably determined by taking and analyzing the reaction solution at regular intervals. For example, the yield of reaction product can be determined in a straightforward manner by analyzing the sample using high pressure liquid chromatography and comparing it to a standard solution. Optimization of the reaction time is recommended because the introduction of unnecessarily prolonged oxygen leads to overoxidation and thereby leading to, for example, decarboxylation and a decrease in the yield of the desired reaction product.

The reaction mixture can be worked up according to conventional methods. For example, first of all the water and optionally the solubilizer present are removed by distillation. Purification is then carried out, for example by chromatography, crystallization or precipitation. From the solution obtained in the oxidation, OH ^- - it can also be separated via the basic ion exchanger in the form. However, it has generally been found preferable to spray dry the solution obtained during the reaction.

The lime binding capacity of the ethercarboxylic acid can be determined by a usual analytical method, for example, turbidimetric titration or potentiometric titration using an ion-specific electrode.

The ethercarboxylic acids obtainable according to the invention are particularly suitable as an additive (builder) in detergents or cleaners. In addition, it can be used as a food additive and as a cross-linking agent in paint preparations.

The present invention relates to a method for producing an ethercarboxylic acid described in claim 1, but the invention described below also
It is included as an embodiment of the invention.

(1) The amount of propylene oxide, butylene oxide or styrene oxide, and the amount of ethylene oxide are up to 3 mol and 1 to 10 mol, respectively, relative to 1 mol of OH in the carbohydrate and its derivative, wherein:
The process according to claim 1, wherein the total amount of alkylene oxide is preferably up to 5 mol.

(2) The process according to any one of claims 1 and (1) above, wherein the catalyst comprises 1 to 15% by weight, preferably 5 to 10% by weight of platinum and a carrier, preferably activated carbon.

(3) Oxidation is 0.5 to 100 bar, preferably atmospheric pressure to 10 bar
The method according to claim 1 and any one of (1) and (2) above, which is carried out in the pressure range of 1, especially at atmospheric pressure.

(4) The aqueous solution contains a solubilizing agent which is inert under the reaction conditions, preferably in an amount of 10 to 75% by weight, particularly 30 to 50% by weight,
The solubilizer is preferably a hydroxyl group-free glycol ether, especially diethylene glycol dimethyl ether.
The method according to any one of (3).

(5) Oxidation is 5 to 80 ° C, preferably 10 to 60 ° C, especially 20
The method according to claim 1 or (1) above, which is performed at a temperature of -40 ° C.
~ The method according to any one of (4).

(6) The method according to any one of claims 1 and (1) to (5) above, wherein the oxidation is carried out at a pH value of 6 to 8.5, preferably 7 to 8.

The following example illustrates the invention.

Example 1-Preparation 450 ml of water in a 2 liter stirred autoclave so that the temperature is 85-100 ° C. and the pressure is up to 4 bar.
To 111 g of saccharose and 2.75 g of KOH in it was added 333 g of ethylene oxide. After a reaction time of 2 hours, the solution was cooled to room temperature and water was added to bring the total volume to 4 liters. This solution was heated from the outside in a vertically arranged glass tube (diameter 100 mm, length 800 mm) to obtain a commercially available catalyst (5% on activated carbon).
After adding 20 g of platinum, frit (Glasfri
gas was treated with 100 NL / h oxygen. By continuously adding a 30% strength aqueous solution of sodium hydroxide,
Kept at 7.5. The oxidation time was 6 hours. Spray drying of the reaction product gave 390 g of a colorless powder (determined at room temperature) with a lime-binding capacity of 279 mg of CaCO ₃ / g of substance.

Example 2-Production As in Example 1, sorbitol (110 g) was mixed with ethylene oxide.
470 g and 4 g of KOH were ethoxylated in 950 ml of water and then oxidized after adding 4.27 l of water and 290 g of catalyst. The spray-dried product (484 g) contains CaCO ₃ 373 per g of substance.
It had a lime-binding capacity of mg.

Example 3-Preparation As in Example 1, pentaerythritol and α-methylglucoside were tested for their lime binding capacity after ethoxylation and oxidation and finishing. The product obtained with pentaerythritol, lime binding capacity of CaCO ₃ 343 mg per material 1g, and those using α- methyl glucoside, had a lime-binding capacity of the CaCO ₃ 327 mg per substance 1g .

REFERENCE EXAMPLE-USE The fact that the product obtained according to the invention excels as a builder is merely due to the fact that the German patent application DE
It can be seen in the test results of the detergent formulation with the product according to the invention of Example 1 instead of the saccharose-tricarboxylic acid obtained according to 3535720. The washing tests of these detergents were carried out according to DIN 44983 and approved industry standards.

Washing capacity (reflectance difference) is 2 kinds of WFK and EMPA
It was determined photometrically by measuring the reflectance of the soiled test cloth at a wavelength of 460 nm (Farbmegert RFC 3 from the Zeiss firm) (WFK = Wscherei-Forschungsinstitut) Krefeld EMPA
= Swiss Federal Institute for Raw Materials (Eidgenssische Material
-Prfanstalt), Switzerland). In this case, the _{equation:% R =% R g -} % by R _u "Differences method (Differenzmethode)" was used.

Among them,% R =% reflectance difference (washing ability)% R _g =% reflectance of washed cloth% R _u =% reflectance of unwashed cloth.

Fabric deposits (Inkrustation) were determined at 800 ° C as a percentage of the burning residue in the form of inorganic fabric ash.

Part of the manufacture of detergent powders is the so-called hot spray method (Hei
sprhverfahren) and in part by the so-called spray mist mixing method (Sprhnebelmischverfahren) (dry mixing method). Thermal spraying was carried out using a laboratory spray dryer (Commercial Bchi, Model 190) with an inlet temperature of about 180 ° C, an outlet temperature of about 100 ° C, a spraying pressure of 5 bar and a solids concentration of 30% by weight. I was broken.

In the case of the spray-mist mixing method, a free-fall mixer was used, in which the liquid constituents were aufgedst on the dry constituents in powder form by means of a suitable spraying device. The procedure is "Se
ifen, Fette, le, Wachse ", 99 , (1973), 351-357.

The detergent formulations and laundry tests are listed in the table below.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical display location C11D 3/20 (72) Inventor Gora Werner Germany, D-5216 Niedel Kassel, Rathausstreller SE, 73 (72) Inventor Dani Franz-Josef, Federal Republic of Germany, Day-5042 Elft Stadt, Headinghof Enerstraße, 47 (72) Inventor, Schlingmann-Merten, Federal Republic of Germany, Day-6240 Konig Stein / Taunus, Schneit Heinel Strasse, 32

Claims (1)

[Claims] 1. A carbohydrate or a derivative thereof is directly ethoxylated in the usual manner or, first of all, alkoxylated with propylene oxide, butylene oxide or styrene oxide and then ethoxylated,
Then, the aqueous solution obtained at that time is treated without further treatment.
Process for the preparation of ether carboxylic acids by alkoxylation of carbohydrates and their derivatives and subsequent oxidation, which comprises oxidizing with oxygen as oxidant in the pH range of 9 in the presence of a catalyst containing platinum.